After Tuesday, the Nasdaq was the only one of the three indices still clinging to a modest gain for the year, but stood at its lowest levels in more than seven months.

"Today was again a big sell-off," said JJ Kinahan, chief market strategist at TD Ameritrade. "Investors are repricing stocks."

Analysts have blamed the weakness on worries about slowing global growth exacerbated by a series of Federal Reserve interest rate hikes and the burgeoning US-China trade dispute. Some market watchers have said the fall has been exacerbated by light trading volumes this week ahead of Thursday's Thanksgiving holidays when markets will be closed.

Most large technology companies dropped again, including Apple and Microsoft, which shed 4.8 percent and 2.8 percent respectively. Amazon and Netflix fell more modestly, while Google parent Alphabet and Facebook advanced modestly in apparent bargain hunting.

Petroleum-linked shares were another weak segment, with Dow members ExxonMobil and Chevron plunging nearly three percent and Apache shedding 5.1 percent.

The losses came after benchmark US oil prices slid 6.6 percent to $53.43 per barrel, the lowest level in more than a year, amid worries over excess supply.